Overview of the geology and geophysics of the Tikishla Park drill hole, USGS A-84-1, Anchorage, Alaska

Yehle, Lynn A.; Odum, Jack K.; Schmoll, Henry R.; Dearborn, Larry L.

doi:10.3133/ofr86293

Cited by 6 publications

(13 citation statements)

References 8 publications

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“…1) drilled to a depth of about 3.5 km failed to penetrate the bedrock. The age of the bedrock ranges from the Upper Palaeozoic to the Upper Mesozoic (Yehle et al 1986). Thick deposits of non‐marine Tertiary sediments, principally composed of sandstone, siltstone and claystone, lie above the bedrock which constitutes a major unit of the Cenozoic sequence beneath the Anchorage lowlands.…”

Section: Geological and Tectonic Setting Of The Areamentioning

confidence: 99%

Three-dimensional imaging of shear wave velocity in the uppermost 30 m of the soil column in Anchorage, Alaska

Badal¹,

Dutta²,

Serón³

et al. 2004

Geophysical Journal International

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S U M M A R YThe main aim of this paper is to obtain an overall view of the shear wave velocity structure of the Anchorage metropolitan area and to analyse in detail the extent of various soils types both laterally and vertically. For this purpose a stochastic scheme has been used to invert the Rayleigh wave phase velocity data to obtain 1-D shear wave velocity structure in the uppermost 0-30 m at 36 sites in the Anchorage Basin, located in south central Alaska. On the basis of these 1-D velocity models we have applied an imaging technique aimed at volumetric modelling and data visualization based on an interpolation algorithm involving finite differences. We present a 3-D representation of the S-wave velocity structure of the Anchorage area obtained through spatial prediction. These velocity images are shown as horizontal slices at gradually increasing depths, vertical cross-sections at various latitudes and longitudes, and 3-D blocks as defined by characteristic velocity ranges. They enable us to understand in detail the different soil classes by their characteristic shear wave velocities. The images are in good agreement with the available geological information about the area.

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Section: Geological and Tectonic Setting Of The Areamentioning

confidence: 99%

Three-dimensional imaging of shear wave velocity in the uppermost 30 m of the soil column in Anchorage, Alaska

Badal¹,

Dutta²,

Serón³

et al. 2004

Geophysical Journal International

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“…Glacial deposits in the map area are the products of several glacial advances from and retreats to distant mountains to the north and east as well as the advance and retreat of local glaciers in major mountain valleys, especially the large valley of Turnagain Arm (Dobrovolny and Miller, 1950;Miller and Dobrovolny, 1959;Karlstrom, 1964;Cederstrom and others, 1964;Reger andUpdike, 1983,1989;Schmoll and Yehle, 1986). Each of these glaciers successively modified the terrain in the map area.…”

Section: Glacial Depositsmentioning

confidence: 99%

“…The glacial deposits are further subdivided and relative ages determined with reference to named lateral and end moraines, as discussed by Schmoll and Yehle (1986). Those authors also discuss difficulties in using the glaciation terminology developed by Karlstrom (1957;1964) in classifying glacial deposits in the Anchorage area and used by Miller and Dobrovolny (1959) and most later workers.…”

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confidence: 99%

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Surficial geologic map of the Anchorage A-8 SE quadrangle, Alaska

Schmoll¹,

Yehle²,

Dobrovolny³

1992

Open-File Report

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“…This indicates that the sedimentary deposits of the basin exceed few kilometers. These deposits range in age from the Upper Paleozoic through the Mesozoic (Yehle et al, 1986) and show widespread lithological variation from the eastern to western side of the city (Combellick, 1999). The sedimentary section immediately overlying the bedrocks is of the Tertiary age and consists of thick deposits of nonmarine sediments.…”

Section: Introductionmentioning

confidence: 99%

Investigation of Shallow Sedimentary Structure of the Anchorage Basin, Alaska, Using Simulated Annealing Inversion of Site Response

Dutta

Sen

Biswas

et al. 2009

Bulletin of the Seismological Society of America

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This study deals with shallow sedimentary structure of the Anchorage basin in Alaska. For this purpose, inversion of site response [SRf] data in the frequency range 0.5-11.0 Hz from various sites of the basin has been performed using the simulated annealing method to compute subsurface layer thickness, shear-wave velocity (β), density, and shear-wave quality factor. The one-dimensional (1D) models for the aforementioned parameters were obtained with preset bounds on the basis of available geological information such that the L-2 norm error between the observed and computed site response attained a global minimum. Next, the spatial distribution of the important parameter β was obtained by interpolating values yielded by the 1D models. The results indicate the presence of three distinct velocity zones as the source of spatial variation of SRf in the Anchorage basin. In the uppermost part of the basin, the β values of fine-grain Quaternary sediments mainly lie in the range of 180-500 m=sec with thickness varying from 15 to 50 m. This formation overlies relatively thick (80-200 m) coarse-grain Quaternary sediments with β values in the range of 600-900 m=sec. These two Quaternary units are, in turn, overlain on Tertiary sediments with β > 1000 m=sec located at depths of 100 and 250 m, respectively, in the central and western side along the Knik Arm parts of the basin. The important implication of the result is that the sources of spatial variation of SRf in the Anchorage basin for the frequency band 0.5-11 Hz, besides in the uppermost 30 m, are found to be deeper than this depth. Thus, use of commonly considered geological formations in the depth intervals from 0 to 30 m for the ground-motion interpretation will likely yield erroneous results in the Anchorage basin.

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Overview of the geology and geophysics of the Tikishla Park drill hole, USGS A-84-1, Anchorage, Alaska

Cited by 6 publications

References 8 publications

Three-dimensional imaging of shear wave velocity in the uppermost 30 m of the soil column in Anchorage, Alaska

Three-dimensional imaging of shear wave velocity in the uppermost 30 m of the soil column in Anchorage, Alaska

Surficial geologic map of the Anchorage A-8 SE quadrangle, Alaska

Investigation of Shallow Sedimentary Structure of the Anchorage Basin, Alaska, Using Simulated Annealing Inversion of Site Response

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